What Could Possibly Go Wrong?
by potterchick338
Summary: Halloween themed one-shot. When Clary finds out that Jace and the others hate Halloween, she is not happy. So Clary decides to have a little fun. It wouldn't hurt anyone to pull a few pranks, right? Might be a little OOC. Rated T cuz I'm paranoid.


**Here's a little Halloween one-shot. I was going to post it yesterday, but I got a little backed up.**

**Disclaimer: Everything belongs to Cassandra Clare**

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><p>Clary had quickly discovered that none of the Lightwoods liked Halloween. The day before when she had talked to everyone about what they wanted to do for Halloween, their answers had annoyed her. Jace had said that Halloween was a stupid holiday that mundanes invented and it pissed him off when they had to go investigate demon sightings and they ended up just being mundanes who had dressed up like monsters. Alec responded by saying that more attacks on mundanes happened on this day than any other day in the year and it was the mundanes faults for doing stupid things. Izzy liked the idea of being able to dress up, but she said that shadowhunters were way too busy and besides, it was just a holiday where people begged for candy.<p>

Clary sighed. She was disappointed in their lack of enthusiasm. Halloween was one of Clary's favorite holidays, and she wasn't about to not do anything. So she decided that she would get back at the Lightwoods by scaring the hell out of them. Clary recruited Simon to help her. She had just finished explaining her plan to the vampire and she looked at her friend expectantly. "So, what do you think?"

Simon shook his head. "I think that Jace will try to murder me."

Clary laughed. "That's what I was going for. He won't actually be able to hurt you Simon." Clary gestured at Simon's forehead, where she had drawn the mark of Cain on him.

"Exactly." Simon said. "He'll try to kill me and then end up dying himself."

"I won't let that happen." Clary frowned. "Are you in?"

Simon sighed. "I guess I don't really have a choice in the matter."

"Well let's get to it." Clary said grinning.

For the next hour, Simon and Clary were preparing for the prank. Luke and Jocelyn were gone for the day, so Clary didn't have to worry about being caught. They put almost everything on Clary's desk and shelves on the ground and turned some of the furniture over, making it look like there had been a struggle. Then they mixed red food dye with vegetable oil to give the liquid the consistency of blood. Clary poured the mixture onto a sheet of plastic that was put on the ground so that the "blood" wouldn't ruin Clary's carpet. Clary covered herself in makeup to make herself look extremely pale. Lastly, Simon drew what looked like two small indents on Clary's neck. Now it was time to make the call.

Clary took out her phone and dialed Jace's number. Jace answered on the second ring, but before he could say anything Clary cried into the phone. "Jace!" She shrieked. Simon gave her a silent thumbs up. Clary took an empty plastic candy wrapper and started rubbing it together to make the phone call sound like there was static.

Jace sounded worried. "Clary! Clary what's wrong?"

Clary didn't respond. She looked over at Simon who then pushed a vase off Clary's desk. Clary didn't really like the vase so she wasn't upset when it hit the ground and shattered into a million pieces, making a huge crash sound in the process. "Oh my god." Clary whispered into the phone. "Jace I'm at my house. Help me."

Simon walked over and pushed the door into Clary's wall as hard as he could. Clary gasped. "He found me. Jace! Help!" Clary let out her most convincing blood curdling scream and snapped the phone closed. She and Simon started to laugh.

Clary looked at Simon. "Now for the finishing touches." Clary picked up her stele and drew a rune that she had invented on her stomach. When she finished, she held her arm out. "Does it work?"

Simon reached out and put two fingers to Clary's wrist. After a moment he smiled. "No pulse. You are officially dead."

Clary smirked and slid her stele across the floor. She laid down in the fake blood and positioned herself so that you couldn't see the plastic. Simon walked over and poured a little of the red mixture on each of the supposed bite marks, making it look like blood was seeping out of them. He put a little more of the liquid on his face and then hid the bowl in Clary's bathroom. Simon sat down on the edge of the bed and waited. Clary slowed her breathing down to make it seem like she wasn't breathing at all.

Before long, they heard the front door open and then slam closed. Clary grinned and then went back to being dead. Simon put his head in his hands. Clary and Simon had made a path of destruction leading to Clary's room so it took little time for Jace to find them. He threw the door open and rushed into the room. He didn't notice Simon at first. All he saw was Clary lying unmoving in a pool of blood. Jace ran over and dropped to his knees beside Clary. He grabbed her wrist and then let out an angry screech when he didn't feel a pulse. Simon sucked in a breath and Jace whipped around at the noise.

"Simon?" He asked in disbelief.

Simon looked at him with guilty eyes. "I didn't mean to." He whispered. "I was so hungry and Clary accidentally cut her finger and I couldn't help myself."

Jace stared at him. "You….killed…..Clary?"

"I didn't mean to." Simon repeated.

Jace pulled out a knife. "You're going to pay." He growled. He took a step towards Simon but then stopped when Clary spoke.

"Jace." Clary whispered before coughing.

Jace ran back to her. Clary's eyelids fluttered open. "Jace…"

"Clary. It's going to be okay. You're going to be okay."

"How do you know?" Clary closed her eyes again.

"No!" Jace cried. "Clary open your eyes! Look at me Clary!"

Clary didn't speak. When Jace was about to get up again, Clary's hand shot out and gripped Jace's wrist. She looked up at him. "Did I scare you?"

"What?" Jace just sat there. What the hell was going on?

Clary smiled and repeated the question. "Did I scare you?"

Jace looked at her and then slowly turned towards Simon, who was also grinning.

"I think we got him pretty good Clary. He seriously wanted to murder me."

Clary laughed and sat up. Jace realized it was all fake and frowned. "Why would you do that to me?"

"It's Halloween." Clary shrugged. "I went a little overboard preparing this, but at least I freaked you out."

Jace stood. He was angry now. "Freaked me out? I thought you were dead!" He screamed at her.

Clary got up and put a hand on Jace's shoulder to calm him down. "It was just a prank. But if you're really upset then I'm sorry."

Jace pulled her in and gave her a desperate kiss. He moved his lips to her ear. "I thought I had lost you. Please don't ever do that again."

Clary nodded. "I'm going to clean up now." She walked over to her bathroom door and turned before entering the room. She smirked at Jace. "Happy Halloween Jace."

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><p><em>One down, two to go. <em>Clary thought as she finished straightening up the house. Jace and Simon had left when she was in the shower, and while Clary was cleaning, she had come up with another trick to pull.

Once everything was put back where it belonged, Clary went into her room and put on her costume. After a little tweaking, Clary looked in the mirror and was pleased to see that she actually looked like one of the demons that shadowhunters killed. Not wanting to put up with a taxi, Clary grabbed her stele and drew a portal.

Within minutes, she was standing in front of the Institute. Clary turned and began walking down the street that led to Taki's. Simon had helped with this prank too. He had called Isabelle and told her to meet him at the restaurant. Clary stopped about halfway between Taki's and the Institute. She ducked into an alleyway and waited for Izzy. About ten minutes later, Clary saw Isabelle walking along the sidewalk. She waited until Izzy had passed the alley and then jumped out, grabbing the girl's shoulders from behind. Isabelle spun around and the next thing Clary knew, pain shot through her shoulder. Clary cried out. Isabelle was about to strike again but stopped when she recognized the voice.

"Clary?"

Clary threw her mask on the ground and grabbed her shoulder. "Fuck!"

Izzy's eyes widened. "By the angel! I'm so sorry Clary!"

Clary glared at Izzy. "What the hell was that for?" She managed to spit out.

"I thought you were a demon. You're lucky that I attacked you with a regular dagger and not a seraph blade. The pain would be a lot worse." Izzy spoke calmly, as if she hadn't just plunged a blade into Clary's arm.

"I don't know. It's pretty bad right now." Clary said sarcastically. She hissed when she tried to shrug her shoulders.

"Stop being such a drama queen."

"A drama queen? YOU STABBED ME!" Clary screeched at Isabelle.

"It was an accident. The wound isn't that bad. Just give me your stele and I'll heal it."

"I left it at my house. My costume doesn't have any pockets. Where's your stele?"

"I don't have it."

Clary let out an angry puff of air. "What do you mean you don't have it? You're the one that said a good shadowhunter always has a stele with them!"

Isabelle rolled her eyes. "Well I wasn't expecting you to attack me. We'll just go back to the Institute and heal you there."

"We'll just go back to the Institute and heal you there." Clary mimicked Izzy.

"You're way overreacting." Isabelle hailed a taxi and gave the address to the driver.

The cabbie looked at Clary's shoulder and then glanced back at Isabelle. "Are you sure you don't want me to take you to a hospital?"

"I'm sure." Izzy snapped at the man.

He shrugged his shoulders. "Whatever. Don't get blood on my seat."

When they made it back to the Institute, Clary and Isabelle went straight into the elevator. When the door opened, they stumbled out of the elevator and began to make their way to the infirmary. Jace and Alec, who were in the kitchen, came out to see what was happening. Jace's eyes widened when they landed on Clary's injured shoulder.

"What happened?" Jace asked as he walked up to Clary. He pulled out his stele.

"Izzy stabbed me." Clary said in an aggravated tone.

Jace turned on Izzy. "What?"

Alec took the stele out of Jace's still outstretched hand and started to draw an _iritze _on Clary's shoulder.

"For the record, Clary was dressed up as a demon and attacked me from behind. What did she think was going to happen?"

Alec finished drawing the rune and laughed. "You seriously did that?"

Clary ground her teeth together. "It's not funny Alec."

"You're right." Jace responded. "It's not. Why would you ever try to scare someone whose natural instinct is to attack first and ask questions later?"

Clary's eyes narrowed. She hated being spoken to as if she was a child. "It's Halloween!" She retorted. "Did you honestly expect me to not prank you guys?"

"No more pranks for you Clary." Jace said sternly.

"You can't tell me what to do! Besides, I haven't even done anything to Alec yet!"

"No. More. Scaring." Jace's voice had a tone of finality in it.

Clary crossed her arms. "We'll see about that." She stomped off in the direction of the room she used when staying at the Institute.

Jace sighed at her retreating figure. "How are going to convince her not to pull anymore tricks?"

"We could scare her." Alec suggested.

The refusal Jace was about to say stuck in his throat. If they scared Clary then she would know how it felt. Then maybe she wouldn't do it anymore. "How?" he asked.

Isabelle smirked evilly. "I have an idea."

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><p>Clary stared out the window. Why was everyone getting so upset? <em>She <em>was the one that was stabbed so _she _should have been the one making a big deal out of everything. Clary had thought that Jace would have came in and lectured her by now. Where was he? Clary crept over to the door and peered out into the hallway. No sign of anyone. Clary stepped out of her room. She was walking towards the kitchen when she saw Church laying in a patch of sun. Clary bent down and started to stroke the cat. "Where is everyone?"

Church looked at her and meowed. He got up and started walking away. Clary jumped up and followed him. Church walked around the entire Institute before taking Clary right back to where they were before. Church plopped down into the exact same patch of sunlight. Apparently the entire Institute was empty.

Clary frowned. She pulled out her phone and called Jace. The phone rang and rang and then went to voicemail. The same thing happened when she called Isabelle and even Alec. She called Simon and Magnus but they didn't answer their phones either.

After deciding to just go home, Clary changed and left the Institute. She called a cab and rode home in silence. When she got to her house, Clary couldn't believe what she was seeing. Red and orange flames licked up the house and were blazing in the yard. Clary gasped and looked around frantically for the culprit. She saw someone in the shadows. When her eyes locked on the person, they stepped forward, revealing Jace. He had a cruel look of pleasure on his face and in his hands were a lighter and gallon of gasoline.

Clary glared and ran up to him, shoving him backwards. "Why would you do this?"

Jace grinned. "You said that pulling pranks was fun. I wanted to see for myself. You're right, this is the most fun I've had in years."

Clary stared at him in horror. "Alec? Izzy?"

Jace's grin widened. "They thought it was a bad idea. But oh well. They can't tell me what to do anymore." He nodded towards the burning building.

Clary's jaw dropped. There's no way Jace would do something like this. He was too kind, too caring. But when she looked at his face, it looked like he actually did do this. Clary took a step back, for the first time in her life, she was truly frightened of Jace. Something came up from behind and grabbed at Clary. She screamed and turned to see an amused Isabelle. "Got you!" She laughed.

Clary looked from Izzy to Jace, who was also laughing. "But my house…"

"It was just a glamour. Look." Jace pointed and sure enough the fire was gone and the house looked completely normal.

Instead of being furious and lashing out, Clary started to laugh. She walked over to Jace and kissed him.

Jace pulled back. He looked confused. "You're not angry or upset?"

Clary just shook her head. "Nope. I'm happy. You guys have finally shown some Halloween spirit."

Jace laughed along with Clary and put his lips back to hers.

Everyone got together and watched scary movies and tried to prank each other for the rest of the night. It was the best Halloween Clary had ever had.

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><p><strong>What'd ya think? I know it's not the best story in the world but please don't be too harsh with the comments... Thanks :) <strong>


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